4metals said:
Harold,
It is interesting to me that you prefer to inquart karat whenever you can.
Well, let's say I used to. I am retired, and have been since 1994. I am no longer involved in refining, nor do I have an interest in refining. I am here to help others where I can. However, I inquarted everything (karat gold), even when it was not necessary. It served more than one purpose, so I didn't consider it a problem.
I think it would help you a great deal to have an understanding of how I started refining for others, and my background. If you're interested, I'll lay it out for you. Most everything I did was for a good reason, so I'll offer my reasoning where it applies.
For starters, I am not a chemist, nor am I educated. I was a terrible student, never doing home work and sleeping in classes regularly. I struggled to get out of high school, not knowing if I'd graduate until I did. I had little interest in being there, although in classes that held my interest, I did quite well. Unfortunately, my interests did not revolve around anything that would improve me in ways that might be significant. On the positive side, I had a keen interest in machining, which become my vocation.
I started refining when it was illegal. As a result, I had to keep a low profile. No one was willing to provide the slightest bit of information, but I had the good fortune to acquire a copy of Hoke's book. Perhaps that will help you understand my processing choices. They may not be what industry uses, but they are effective and easy, yielding very acceptable results, as you might see by the quality of gold I have posted in pictures. Best of all, inquartation avoids the problem of high silver content.
I have successfully refined thousands of ounces of karat gold without inquarting.
Understood, and I appreciate the fact that it's possible in a large operation---but one that operated as mine did, that wasn't always an option. I'll try to comment on that as it becomes appropriate.
Here in the East refining rates are competitive and the most a refiner can hope to charge is 2%.
Yes, 2%, but no mention of the other charges. Major refiners do not refine for the average customer for 2%, nor for 10%. The extra charges insure that they make a healthy profit--and they steal beyond that. I have dealt with enough major refiners to know that they are not to be trusted. I hesitate to mention names, but you'd be familiar with all of them, for they are all in the east.
Possibly for that reason I have never inquarted for standard aqua regia refining of karat gold.
Yes, I understand, but in order for any of this to make sense, you must abandon your concept of doing business. I allowed a business model to develop as was required. That was easy. All I did is apply the same procedure to the incoming work that had worked successfully for me in refining the values I could accumulate. Inquarting, for me, was an excellent idea, for sterling was very much a part of the material I received, so it was used in inquartation in order to process for the customer. That way, the silver was used for a purpose, not processed for the sake of processing. In a sense, it was getting two cats with one stone. It made all kinds of sense at my level of operation----and I'd do it again today, given like circumstances. I liked the processes I used, and was very comfortable using them. Remember, I did not, nor do I, have the ability to work things out chemically. I am very good at following procedures that are laid out for me, however.
Back to your business model---when you have limited supply, you are not afforded the luxury of waiting for enough to accumulate in order to selectively combine and melt. A great deal of my success revolved around my fast return and the excellent service I make mention of. For years, I ran my refining as a hobby---making my living at my chosen trade, that of being a machinist/toolmaker. I had my own business, and specialized in the aero-space industry, along with defense work. I also did a small amount for the pharmaceutical industry through various accounts. My expertise was in small, precision work. Refining, to me, was a way to get away from my routine. It was never intended to be a business.
I processed each batch individually, with no assaying involved. Considering it was not uncommon to have dental gold as a part of the submitted material, I used silver as the carrier of platinum group values, so they were collected and concentrated such that they could be recovered easily when the silver was parted. It also permitted running batches, regardless of content. So then, you might rightfully conclude that in my case, inquartation was the best possible choice. It required no special handling---all batches received identical treatment, which became routine. There were far more benefits than negatives, at least in my mind. I had experienced dissolving karat gold directly and was not overly impressed. That was my method of processing filings.
The expense of the nitric dissolve on top of the aqua regia dissolve adds to the cost.
Moot point. As I said, the silver had to be parted, anyway. I also enjoyed the fact that my solutions were not heavily laden with contamination, so there was less drag-down of unwanted substances. I was also paying $4/gallon for nitric, and just over $1 for HCl.
Another trick to gain purity in the precipitation is chilling of the loaded aqua regia. If the acid is cooled to 50 degrees before filtering (ice works for this) the solubility of any silver chloride dissolved in the warm acid drops way down so it can be filtered out easily.
I precipitated from concentrated solutions, heavily iced. My routine when re-refining was to end up with anywhere from 15 to 18 ounces in a liter, which had three liters of ice added prior to precipitation. It was evident when adding ice that a trace of silver chloride was precipitated, but I also washed my gold with ammonium hydroxide in the final wash stage, so that was, for the most part, removed.
The gold is dropped with sulfur dioxide gas
I, too, used sulfur dioxide. I had a large cylinder that was plumbed from the main floor of my operation to the lab, which was upstairs. Only in my early learning years did I use anything else, which was ferrous sulfate. I didn't like using it because of the volume increase.
the nitric is driven off by gassing because we never use urea in a system of my making.
Never in my more than 20 years of refining did I use urea. I evaporated routinely, using a button of added pure gold to consume traces of excess nitric. Because of my method, I had to evaporate, so adding the button was added insurance, and permitted evaporating for concentration instead of for expulsion of nitric.
The gold is transferred <clip very interesting process>
You may understand that an operation that deals in low volume would not be suited to that procedure. Again, I suggest you abandon your concepts in this case. What I did was very successful, in spite of it being out of the ordinary. While I refined for over 20 years, the last ten years, refining was my sole source of income, and I had no problem selling the operation. It was not even advertised.
My washing procedure consisted of a heavy boil in HCl, a boil in tap water to rinse (our water was relatively clean), a boil in ammonium hydroxide, a boil in tap water, a boil in reagent grade HCl, then another rinse in tap water. The gold was then force dried in the beaker by slow evaporation. Only minute traces of water hardness was observed, and the gold melted without oxides (no fluxing aside from coating the dish). The picture I posted is gold from that very process, and was the last gold I refined before selling the operation.
Gold produced by this method consistently assays .9997 plus (Ledoux ICP) after melting.
Only on one occasion was my gold assayed, and I have no idea where the assay was performed. One of my customers, when he (they, two guys) first used my services, were concerned about my quality. They claim it assayed 9997. I have no way of knowing if that is true, or not, but the fact that there is no oxidation is a strong indicator that it is.
We claim .9995 and nobody ever has challenged the purity.
My packaging labels also claimed 9995. The only challenge was described, above. I had an excellent reputation for quality, honesty and fast delivery. Believe it or not, my business model worked very well.
So then, it can be safely concluded that a small operation is unlikely to emulate a large one, and if an attempt is made to do so, it may well not succeed.
Key to my success was my service. I picked up and delivered, and offered three day service in the beginning. As the operation grew, I could no longer provide the short service, but with rare exception, I did provide seven day service. I always offered an advance of gold if the customer was in need, and sold gold to or for them at spot price, free of fees. Buyer and seller alike got a fair deal, although I restricted my sales to my customers.
The majority of my customers were small operations, so they submitted small lots, so I had to tailor the operation accordingly. I processed a lot of gold only because of my years of refining, and because of the large customer base. Regardless of how you perceive the operation, it was a resounding success, particularly when it was never intended to be a business. In the end, it had grown so large that I was working long, hard days, 365/7. Christmas day was just another work day for us (my wife and me).
For the record, I processed solutions, polishing wastes, floor sweeps and carpets. I offered all the services my customers required for their humble operations.
What I had was a strong work ethic, coupled with a streak of honesty. You can't miss with that combination.
Harold
